Purification of plasminogen



United States Patent 3,340,156 PURIFICATION OF PLASMINOGEN Villy Johannes Jensen, Vanlose, Denmark, assignor to Novo T erapeutisk Laboratorium A/ S, Copenhagen, Denmark, a Danish joint-stock company No Drawing. Filed Apr. 19, 1965, Ser. No. 449,328 Claims priority, application Great Britain, Apr. 28, 1964, 17,649/64 8 Claims. (Cl. 19566) ABSTRACT OF THE DISCLOSURE The invention provides a process for the purification of human or animal plasminogen by employing an aliphatic amino acid for distributing the plasminogen and the accompanying impurities, respectively, between an anion exchanger phase and a phase of a water-miscible polymer, whereby a considerably purified plasminogen is obtained.

The present invention relates to a process for the purification of impure plasminogen.

It is know that human plasminogen may be purified by a modification of the Kline method followed either by gel filtration through dextran columns or by chromatography on DEAE-dextran columns (diethylaminoethyl dextran).

Furthermore, human plasminogen has also been purified by means of diethylaminoethyl cellulose ion exchangers employing lysine for displacing the plasminogen from the columns prior to displacement of undesired impurities in the form of other proteins.

Thus, DEAE-cellulose may be suspended in an ammonium acetate butfer solution of pH about 9 and containing lysine to a concentration of 0.01 M, whereafter human plasminogen which has already been purified partially is dissolved in the above butler and applied to a column containing the above suspension. When the column is developed with ammonium acetate buffer containing lysine there is obtained a fraction containing the main part ofthe caseinolytic and fibrinolytic activity, but only a small part of the other proteins.

It has further been established that dextran is able to form two-phase systems with other polymers. As an example, when g. of dextran G 25 and 5 g. of polyethylene glycol having a molecular weight of 6000 are added to 100 ml. of water and the resulting system is stirred or otherwise agitated, the system will separate into two phases after centrifugalization or following standing for some time. The upper phase mainly consists of polyethylene glycol while the main part of the lower phase is the dextran G 25 It has also been established that many proteins are dissolved in the dextran-polyethylene glycol system, and that the distribution of proteins between the two phases depends upon the molecular weight fraction of the polymers and also to a considerable degree upon the salt content. Thus, a protein may be transferred from one phase to another merely by changing the ionic composition of the phase system.

In accordance with the present invention it has now been found that impure plasminogen of human or animal origin can be purified to a considerable extent by employing an aliphatic amino acid for distributing the plasminogen and the accompanying impurities, respectively, between two phases one of which is an anion exchanger and the other is a water miscible high molecular compound, whereafter the latter phase is isolated.

It has been found that when impure plasminogen is treated in the above manner the aliphatic amino acid acts to concentrate the plasminogen in the phase comprising the water-miscible high molecular compound while the main part of the impurities is concentrated in the anion exchanger phase. The amino acid employed should, of course, be compatible with the plasminogen, i.e. it should be selected among those aliphatic amino acids which do not deactivate or denature the plasminogen.

The two-phase system formed by the water-miscible high molecular compound and the anion exchanger may be a liquid-liquid system or a liquid-solid system, depending upon the specific high molecular compound and anion exchanger employed. In case a two-phase liquid system is formed, the purified plasminogen will be concentrated in the upper phase which mainly consists of the water-miscible high molecular compound. As an example, in the system polyethylene glycol-dextran the plasminogen will be found in the upper polyethylene glycol phase. If, for example, an anion exchanger of the solid Amberlite type, such as IRA-400 is employed together with, say, polyethylene glycol, the plasminogen will also concentrate in the polyethylene glycol phase, the solid anion exchanger collecting as a solid bottom phase.

The fact that the plasminogen is concentrated in the upper phase is of considerable practical advantage because the said phase has a comparatively low viscosity and, therefore, is convenient to handle. In case the employed anion exchanger is of the dextran type, the lower phase is often very similar to a gel and is thus diflicult to handle. When an amberlite anion exchanger resin is employed, the lower phase is a solid phase.

In contradistinction to purification on dextran columns which ordinarily are difficult to handle on a technical scale due to minute flow rates, it is advantageous to deal with a two-phase system which by batchwise operation can be separated into two phases. According to the invention also significantly greater yields can be obtained in comparison with the traditional methods of purification.

When human or animal plasminogen is purified in the manner described above the degree of purification obtained is sufficiently high for ordinary purposes to make further purification superfluous. Thus, the plasminogen which has been purified according to the method of the present invention may be used directly for activation to plasmin without the relatively large number of dissolution and precipitation procedures generally necessary in order to purify plasminogen which has been precipitated from blood serum.

As mentioned above the anion exchanger may be selected among various types among which there may be mentioned anion exchangers of the dextran type, e.g. the so-called DEAE-dextran, and anion exchanger resins of the well-known amberlite series, for example Amberlite IRA-400, and an anion exchanger of the cellulose type, for example DEAE-cellulose.

The water-miscible high molecular compound employed in the present process for forming the upper phase of the two-phase system may also be selected among a great variety of compounds, such as polyethylene glycol, polyvinyl py-rrolidone and methylcellulose. In connection with an anion exchanger phase consisting of DEAE- dextran it has been found to be especially appropriate to employ polyethylene glycol for forming the second phase. Experiments made seem to indicate that polyethylene glycol is also efficient in the case of amberlite anion exchanger resins.

As regards the aliphatic amino acids which may be amployed for the purpose of distributing the plasminogen between the two phases referred to in the foregoing, such amino acids as lysine, 'y-amino butyric acid, ornithine, e-fillllllO caproic acid and arginine have been found to be particularly well suited, especially lysine. However, still further aliphatic amino acids may be used, e.g.

3 glycine, guanidino acetic acid, creatine, fl-alanine, DL- valine, DL-leucine, DL-isoleucine, DL-norleucine, L(+)- aspartic acid, L(+)-citrulline, otN-acetyl-L-arginine and glycyl glycine.

ethylaminoethyl dextran and polyethylene glycol (molecular weight 6000) were added to 20 ml. portions of plasminogen solutions which were prepared from plasminogen precipitated from pigs serum at C. and pH 6.0 by

When carrying out the process of the present invention 5 means of 20 percent ethanol. The pH was adjusted to a in practice it is preferred to employ an aliphatic amino given value, and the solution was left for minutes at acid of the type having a terminal amino group and a room temperature and was then centrifuged at the same terminal carboxyl group in the main chain of the molecule, temperature. The upper phase was separated and the volpreferably with 5 to 6 carbon atoms in the main hain, ume thereof was measured whereafter this phase was ana- The relative amounts of the amino acid, the water 10 lyled in the following manner! miscible high molecular compound and the nio e The plasmin activity was determined after activating the changer may vary considerably depending upon the speciplasminogen with urokinase, and the total plasmin acfic compounds selected in each instance. However, an tiVitY was then Calculated in Percent of the plasmin experiment on a small laboratory scale will generally be tiyity the Original Plasmhlogen Sohltteh- The P sutficient to establish the appropriate relative amounts of age thus calculated is equal to the yield Y in the present the above components. As to the high molecular compound p it should be noted, however, that in case a relatively low The pr in Concentration W determined as y in molecular weight is chosen, e.g. of polyethylene glycol, the yp p at 230 ill N Q y measuring the compound will mostly have to be employed in relatively Optical density (CD280) 0f the experimental Solution large concentrations. compared with the optical densities of standard solutions It is preferred to employ the anion exchanger in Containing Varying known amounts of P amounts ranging from about 0.1 t bo t 10 percent f The specific plasmin activity was calculated as the numthe pla s rninogen starting solution. If the anion exchanger ber of plasmin units P CD280: the experimental p is a resin it may be desirable to use this in a still higher dehsity being corrected y means of the bhhd Value, concentration, e.g. up to about 30 percent. The reason the 280 Of the SysteIn When containing no Protein at therefo-r is that the resin does not swell so much as the The efieetivity as regards the Phfifieation 0f Plasmihogeh other mentioned types of io exchangers so h th was calculated as the so-called enrichment factor E showresin will not bind so much of th aqueous phase as d ing the number of times the specific activity was increased the other mentioned types of anion exchangers. The in the Present P amount of water-miscible high molecular compound is In the experiments the results of which are compiled in dependent upon the nature of the specific compound emthe following tables diethylaminoethyl dextran of the type ployed and especially upon the molecular weight thereof. DEAE-Sephadex A-50 Medium was employed as the The amino acid is preferably employed in an amount less anion exchanger phase. In the experimental series forming than about 1 mole per litre of the plasminogen starting the basis of Table III the dextran was washed with distilled S0111ti011- water and then freeze-dried before use. Hereby the smal- Th plasminogen hi h i t b ifi d may b f h lest possible blind value for the CD was obtained. The man or animal origin. Preferably plasminogen isolated above deXtTah usually liberates. compounds h from pigs blood is employed. The plasminogen may thus Viblet absorption y shlfl'yihg iIl Watef- The W r C0 1- be precipitated f o serum plasma f ig blood by 40 tent of the freeze-dried dextran was 10.8 percent, whereas dil i 5 to 3 times i Water at a PI-Lvalue f 5 as the normal dextran has a water content of 4.9 percent. disclosed in U.S. patent application No. 327,339. Further- The P e yl glycol employed in the experiments more, the process of the invention may be employed in the was a sheltpl'odllet of the WW PEG 6000' i a Wat r purification of plasminogen which has been precipitated content of P from serum or plasma from pigs blood by adding an orh eXpel'hhehtal results Set forth in Table I w re ganic solvent such as ethanol in an amount of at least 10 Obtained y employing a lysine Concentration, of 111018 percent at a pH of 5-9 and at a temperature between the p r l a diethylaminoethyl deXtran ntr ti n of freezing point of the mixture and about 15 C, This 3.75 percent, and a polyethylene glycol concentration of process is disclosed in U.S. patent application No. 380,488. 3.75 percent, the pH-value being varied between 2.0 and In the following experiments lysine and thereafter di- 10.0.

TABLE I ssen I an ease PH ee an-:

per liter per 20 ml. percent 20 ml. phase, 111. per m1. total 0. 20 750 3. 750 3. 15 6. 0 ii i: g

8.0 ii iii liii See footnotes at end of tables.

TABLE IContinued lflasmin Plasmin Blind value Plasmin units Enrichment factor E Experimental activity, peractivity, ODm oi ODzso CD210 Der series N 0. cent of startaverage corrected CD110 mg solution percent Single determ. Average same results are obtained when employing a pH-value The results set forth in Table II were obtained using the same concentations of diethylaminoethyl dextran and polyethylene glycol as above. However, the pH-value was kept constant at 8.0, whereas the lysine concentration was varied from 0.05 to 0.25 mole per litre.

Experimental series No. 3: 100% activity-20.0 plasmin units. Specific activity of starting product: 0.100 plasmin units per CD 25 It appears from Table II below that the yield is increased when the lysine concentration is brought up from 0.05 to 0.25 mole per litre. However, the enrichment factor E shows its maximum value at a lysine concentration of about 0.1 mole per litre. At the latter lysine concen- 30 tration the yield is about 34 percent, only.

In the experiments the results of which have been summarized in Table III a lysine concentration of 0.2 mole per litre and a pH-value of 8.0 were employed, whereas the concentrations of the diethylaminoethyl dextran and the polyethylene glycol were varied.

TABLE 11 DEAE- PEG Volume Plasmin Dextran, DEAE- 6,000, PEG Lysine, of upper Plasrnin Plasmin Plasnlin Blind CD410 units per EnrichpH mg. per Dextran, mg. 6,000, moles phase units units, activity, ODm value of corrected ODrao ment 20 percent 2133-1 percent per liter in per m1. total percent ODm corrected factorE 0. 05 11 0. 132 1. 452 7. 12 1. 05 0. 540 0. 510 0. 259 2. 77 0. 10 12 0. 575 5. 910 33. 9 1.80 0. 505 1. 295 0. 445 4. 8. 0 750 3. 75 750 3. 75 o. 15 13 0. 982 12. 10 59. 3 3. 030 0. 517 2. 515 0. 371 3. 0. 20 14 1. 010 14. 10 59. 1 3. 75 0. 550 a. 190 o. 317 3. 39 0. 25 14 1.050 14.80 72.5 5.180 0.590 4.590 0.231 2.47

% activity-20.4 plasmin units. Specific activity of starting product: 0.0936 plamnin units per CD180.

TABLEIII Plasrnin units Total plasmin Plas- CD280 Blind value DEAE- DEAE- PEG PEG Volume per ml. units min of OD Plas- 13n- Dextran, Dex- 6,000, 6,000, of actl- CD250 m n richmg. per tran, mg. perupper vity, I corunits ment 2 ml. perpail cent phi-318 Sligle Aversllgle Averper; sllgle Averslclllgle Averreeted 01351 tacitor cent 20 in eage 5- age cen eage 9- age term. term. term. term. corr.

8 1.590 .7 1,000 5.00 250 1.25 9 M50 }1.520 {13.1 12.9 62.8 {Z500 }7. 688 }0.248 7.440 0.204 2.10 15 1. 190 19. 0 5. 180 .2 250 1.25 525 3.13 L070 }1.180 18.5 90.5 22 g }5. 128 }0.231 5.897 0.192 1.98

11 1.210 13.3 r 1,000 5.00 525 3.13 11 L250 }1.280 }18.5 55.2 }3.050 }0.289 2.771 0.444 4.58 9 1.200 1,375 6.88 525 3.13 9 L280 }1.240 5 }11.2 54.5 {2.500 }2.a00 }0.850 1.940 0.639 6.59

18 0. 780 14. o 2. 880 2 250 1.25 1,000 5.00 18 M48 }0.804 }15.5 75.9 gig }2.828 }0.251 2.557 0.337 3.47

12 0.712 8.5 1,000 5.00 1,000 5.00 13 g, }0.782 9.15 445 }1.258 %0.345 0.918 0.797 8.22 9 0.7 2 1,375 5.88 1,000 5.00 10 M68 }0.700 M8 5.54 32.3 {L110 }1.120 0 384 0.736 0.951 9.80

13 0.300 1 3.90 0.775 1,000 5.00 1,375 6.88 13 0,372 0.385 4.37 21.3 38 }0. 788 }0.390 0.398 0.844 8.70 1,575 6.88 1,375 5.88 {gig }0.274 3 2g 2.50 12.5 E }0. 702 {01444 }0.420 0.282 0.971 10.00

100% activity-20.54 plasmin units. Specific activity of starting product: 0.0970 plasmin units per ODm.

Enrichment 7 factor E LZLLLLZZZRW ODm corr.

corrected Blind LLLLZZZZnm v I ht 7 265183 mmm &868270Q LLLLLZLZZ E S m 472455859 .780804 26 mmmmm 112122. L22 .luDOc 000000000 P 0 d 8 no 11778 mwm 8%67608$% O R 788777665 m e 539915074 u 246726793 m V Blind value of CD 50 0 0 Q0 0 0 00 LL Dzsu Plasminactivity, percent activity, percent experiments polyvinyl pyrrolidone was used instead of polyethylene glycol. It appears from the table that a certain degree of purification is obtained in this manner.

The results appearing in Table V were obtained by employing methyl cellulose as the water-soluble high molecular component of the two-phase system. This table shows that enrichment factors of the same magnitude as above were obtained. a

In Table VI there are shown results of experiments in which a two-phase system of DEAE-dextran and polyethylene glycol was employed in combination with amino acids other than lysine. It is seen from this table that the use of a-aminobutyric acid and of e-amino caproic acid gives results corresponding to those obtained with lysine, whereas the use of ornithine gives a somewhat smaller enrichment factor. However, it is quite possible that a higher ornithine concentration will lead to a higher degree of purification.

Plasmin units, 'total units, total eeaazaae tion 5 TABLE IV Plasmin units per ml.

TABLE V units per ml.

in connec he dextran combtained an g the diethyl- 8.0; lysine concentration 0.2 moles per liter; t- G.

Volume of upper 8.0; lysine concentration: 0.2 moles per liter; t-25 C.

Volume Plasmin 'Plasmin Plasmin of upper phase, ml.

5000500555 QMAMALLLLLLZ 111111111 there is 0 ell as a yield of pyrrolidon, percent 5055550055 0 LLL0 0 LLLL Poiyvinyl- Polyvinylpyrrolidon, mg. per 20 m1.

Methylcellulose,

mg. per 20 ml.

y purified when employing sufliciently high DEAE- Dextran,

percent mmmmmwmmw It appears from Table III that the plasminogen may be In the experiments the results of which are compiled in Table IV a pH-value of 8.0 and a lysine concentration DEAE- Dextran, mg. per 20 ml.

considerabl concentrations of diethylaminoethy'l dextran and polyethylene glycol as well as lysine. Thus, when employing a lysine concentration of 0.2 mole per litre with 5 percent concentrations of both t pound and the polyethylene glycol enrichment factor as high as 8.2 as W about 45 percent. However, the total yield may be increased up to about percent by shakin aminoethyl dextran phase once more with a fresh portion of polyethylene glycol, whereby additional 23 percent may be recovered. Thus, the present method of purifying plasminogen can be utilized to obtain a high enrichment factor and a high yield at the same time.

of 0.2 mole per litre were employed. However, in these activity-22.2 plasminunits. Specific activity of starting product: 0.111 plasmin units per ODzsu. Polyvinylpyrrolidon employed: Kollldon 17 {tom BASF (with 5.28% H10).

DEAE- Dextran,

mg. per 20 ml.

LLLL 1 1- ment factor E Plasmin Enrichunits per ODzau corrected activity, OD

percent units, total Volume 0! upper phase, m1.

C USP 25 cps. from Fluka AG.

Concentration of amino acid, moles per liter 100% activity-16.8 plasmin units. s ficific activity of starting product: 0.0904 plasmin units per ODm: Methyicellulose employed: Methocel Amino acid 100% activity-3L6 plasmin units. Specific activity of starting product: 0.111 plasmiu units per OD -Aminobutyric acid- Ornithin-hydrochioride e-Aminocaproic acid.-

in the proclasminogen produced inc 10 Table IX below illustrates the results in connection with the purification of crude human plasminogen which was obtained from human serum in the same manner as the crude bovine plasminogen mentioned above.

Furthermore, experiments have been carried out to show that resin ion exchangers may be used ess of the invention. The employed exchanger was Resine Amberlite IRA-400 (Cl) from Prolabo, Rhone-Poulenc, France. This Amberlite is a strong anion exchanger. The impure plasminogen was porcine p as described in connection with Table VII, and the am acid was lysine used in a concentration of 0.2 mole per litre. The temperature during the experiments was 25 C. The results are compiled in Table X below. 15 The experiments show that optimal purification is obtained at pH 6.0 while with the use of the dextran ion TABLE VII ine concentration mo acid used was In these experiments the argin Similarly experiments have also been carried out with The operativeness of the process of the invention in m mE hm 22 f E n m 1 um um 0 0 f m. 0 mm 2 m o 2 L m e m m vD do Hf 22 H0 B o n m w .2 v. MR 07 h 0 6 mm 32 a S m mm 01 t 8 6 mm 11 P s m mm m ma LL mo. 1 P

8 mm mm. mm nu n 0 argmine. was 0.2. mole per litre; besides, the experimental conditions were as reported in connection with Table VI. The results of these experiments appear from Table VII below. 5

connection with the purification of bovine plasminogen appears from the experiments reported in Table VIII below. In these experiments the am lysine in a concentration of 0.2 mole per litre. The crude bovine plasminogen was obtained from bovine serum, which was diluted times its volume with water at pH 5.3 to form a precepitate which was separated and dis solved in water. The experiments were carried out at a pH of 8.0 and a temperature of C.

Enrichment factor E Blind Plasmin value of CD250 units per ODzso corr. ODzso corr.

ment factor E ment factor E Plasmin Enrichunits per OD2EU corr.

Plasmin Enrichunits per CD250 001T.

CD220 corr.

Q m corr.

Blind value of 250 Blind val. of m ODaso Percent activity activity activity units units in total units in total 72217903133447.0153 2 l L 9225 21 9 4 792 a9 66 TABLE VIII units per ml. in total TABLE IX units per ml.

TABLE X units per ml.

Volume Plasmin Plasmin phase, ml.

9 888999999 wwlwmnmmmlllllllll PE G-6,000, of upper percent PE G- 6,000, percent PE G 6,000, percent PE G-6,000, mg. per 20 m1.

PE G- 6,000, mg. per 20 m1.

PE G 6,000, mg. per 20 ml.

mmmm mmmwmmmmmmm 00 225577 0000 DEAE- dextran, percent DEAE- dextran,

mg. percent IRA-400, percent 2 5 0 i0 0 0 0 0 0 0 0 0 &0 fl0 111111111111111 DEAE- dextran, mg. per 20 ml.

% activity-60.0 plasmin units. Specific activity of starting product: 0.300.

DEAE- dextran, mg. per 20 ml.

111.1400, mg. per

0000000000 00 0 wmmmmmmmmmmmm mmmm 1 2 3 22222221221221 100% activity-21.6 plasmin units. Specific activity of starting product: 0.0438

Lysine concentration in mole per litre 100% activity-59.2 plasmin units. Specific activity of starting product: 0.0807.

000000000000000000 S &&&&Rw&8 &&om&4 4 &6 m

100% activity-165.8 plasmin units. Specific activity of starting product: 0.311.

1 1 exchanger practically the same purification was obtained in the pH-range of 6 to 8. The experiments also show that the purification obtained depends on the polyethylene glycol concentration. At pH 8.0 the enrichment factor E 12 1 millilitre of the plasmin solution the activity of which is to be determined and the pH of which is 7.5 is added to two test tubes each containing in 0.4 molar phosphate *bufier (pH 7.50) 1 millilitre of a 3 percent solution of increases from about 1.4 to about 2.7 when the PEG 5 Hammarsten Casein said solution having been preheated 6000 concentrauon increases from zero per cent to 3.75 to 35.5 C. After standing for 2 minutes in thermostat percent. at 35.5 C. there are added to one of the tubes 3 millilitres Experiments have also been carried out with a cellulose of a 1.7 molar solution of perchloric acid in distilled water, ion exchanger, viz. DEAE-cellulose (Powder DE 50 from and after standing for 22 minutes at 35.5 C. there is added Whatmann in Great Britain) In these experiments use was to the other tube the same quantity of perchloric acid solumade of the same crude porcine plasminogen as that used tion. By the addition of the perchloric acid a precipitation in the foregoing experiments. The amino acid was lysine takes place, and the two test tubes now stand for 20 minutes used in a concentration of 0.2 mole per litre. The pH- whereafter filtration two times through filtering paper value was 8.0 and the temperature 25 C. The results (I. H. Munktells unrivalled Genuine Swedish Filtering are compiled in Table XI below. Paper No. 0.9 cm.) is carried out. The extinction of the TABLE XI DEAE- DEAE- PEG-6,000, PE G-6,000, Vol. of Plasmin Plasmin Percent Blind Plasmin Enrichcellulose, mg. cellulose, mg. per percent upper units units activity ODzso Val. 01 OD units ment per m1. percent 20 ml. phase, ml. per ml. in total ODm corr. per factor E ODzsucOrr.

100% activity-27.2 plasmin units. Specific activity of starting product: 0.136.

glycol having a molecular weight of 400 and being obtainable from Shell. The plasminogen to be purified was crude porcine plasminogen obtained as mentioned above, the amino acid was lysine used in a concentration of 0.2 mole per litre, and the ion exchanger was DEAE-dextran used in a concentration of 5.0 percent. The pH-value was 8.0 and the temperature C.

two solutions is thereafter measured at 275 my. in a Beckman DU Spectrophotometer (1 cm. quartz cuvette), the value of the sample having stood for 2 minutes being used as blind value. The plasmin solution the activity of which is to be determined in diluted to such an extent that the extinction does not exceed 0.5 as at higher plasmin concentrations no proportionality exists between the extinction and the plasmin concentration.

I claim:

1. A process for the purification of human or animal plasminogen, comprising admixing the plasminogen with an aliphatic amino acid compatible with the plasminogen, an anion exchanger and a Water-miscible polymer, whereby the plasminogen and the accompanying impurities are TABLE XII Plasmin PE G400, PE G400, Vol. of Plasmm Plasrnm Blind units per Enrichml. per 20 percent upper units units 111 Percent ODzso val. of ODnu 01)2E0 ment ml. in total by vol. phase per ml. total activity ODm con. corrected factor E O 0 9 1. 30 11. 7 62. 9 14. 2 2. 15 12. 05 0. 108 1. l6 2 20 10 1. 28 12. 8 68. 8 11. 2 2. 20 9.00 0. 142 l. 56 4 40 10 1. 30 13.0 69. 9 4. 40 2. 30 2. 10 0. 619 6. 65 6 60 9 1. 00 9.00 48. 4 2. 80 2. 20 0. 80 1. 25 13. 4 8 80 10 0. 660 6. 60 35. 5 2. 80 2. 30 0.60 1. 10 11. 1 10 100 11 0. 184 2. 02 10. 9 2. 40 2. 25 0. 15 1. 23 13. 2

100% activity-18.6 plasmin units. Specific activity of starting product: 0.093.

As it will appear from the results a polymer having a relatively low molecular weight will have to be used in considerably higher concentrations than a polymer having a relatively high molecular weight, such as for instance PEG 6000. In order to obtain an E-value of about 6.0 it is necessary to use PEG 400 in an amount of about 40 percent by volume, while the same E-value may be obtained with PEG 6000 in a concentration of 4 to 5 percent by weight.

Throughout the present specification the plasmin activity has been expressed in plasmin units. One plasmin unit is defined as the amount of plasmin causing in 20 minutes the formation of decomposition products being soluble in perchloric acid and having an extinction of 1 unit at 275 mu under the following experimental conditions:

distributed, respectively between two phases one of which is the anion exchanger and the other of which is the watermiscible polymer, and then isolating the water-miscible polymer phase. a

2. A process according to claim 1, in which the aliphatic amino acid has a terminal amino group and a terminal carboxylic group in the main chain of the molecule.

3. A process according to claim 2, in which the aliphatic amino acid has 5 to 6 carbon atoms in the main chain of the molecule.

4. A process according to claim 2, in which the aliphatic amino acid is selected from the group consisting of lysine, 'y-amino butyric acid, ornithine and e-amino caproic acid.

5. A process according to claim 4, in which the anion exchanger is of the dextran type.

13 14 6. A process according to claim 4, in which the anion References Cited exchanger is of the amberlite type. UNITED STATES PATENTS 7. A process according to claim 4, in which the anion exchanger is of the cellulose type.

8. A process according to claim 1, in which the watermiscible polymer is selected from the group consisting of 5 LOUIS MONACELL P'lmary Exammer polyethylene glycol, methyl cellulose and polyvinyl pyr- L. M. SHAPIRO, Examiner. rolidone.

3,066,079 11/1962 Hagan et a1 195-66 

1. A PROCESS FOR THE PURIFICATION OF HUMAN OR ANIMAL PLASMINOGEN, COMPRISING ADMIXING THE PLASMINOGEN WITH AN ALIPHATIC AMINO ACID COMPLATIBLE WITH THE PLASMINOGEN, AN ANION EXCHANGER AND A WATER-MISCIBLE POLYMER, WHEREBY THE PLASMINOGEN AND THE ACCOMPANYING INPURITIES ARE DISTRIBUTED, RESPECTIVELY BETWEEN TWO PHASES ONE OF WHICH IS THE ANION EXCHANGER AND THE OTHER OF WHICH IS THE WATERMISCIBLE POLYMER, AND THEN ISOLATING THE WATER-MISCIBLE POLYMER PHASE. 